Brushcutter attachment for chain saw engine drive



United States Patent lnventor Arshag Hovhannesian Keene, New HampshireAppl. No. 633,117 Filed April 24, 1967 Patented Oct. 13, 1970 I AssigneeRowco Manufacturing Company, Inc.,

Keene, New Hampshire a corporation of New Hampshire BRUSHCUTTERATTACHMENT FOR CHAIN SAW ENGINE DRIVE 10 Claims, 3 Drawing Figs.

US. Cl 143/43, 143/32 Int. Cl B27b 5/02, 9/00. 17/00 Field of Search143/32,

32-14, 43, 43 1.1, 43 34: l56/(lnquired): 64/10130/(lnquired) [56]References Cited UNITED STATES PATENTS 2,810,409 10/1957 lbelle et al.l43/32X 2,908,153 10/1959 Kolls et a1. 64/10X 3,291,167 12/1966 Jarden143/32 3,05 9,491 10/1962 Hoff et a1 143/32 FORElGN PATENTS 612,9811/1961 Canada 143/32 935,865 12/1955 Germany 143/3214UX PrimaryExaminer-Donald R. Schran Attorney-Alfred Musumeci ABSTRACT: A powertool arrangement wherein a brushcutter attachment consisting of anelongated tubular configuration having a cutting saw or other operatingmember at one end is adapted at its opposite end to utilize an ordinarychain saw engine by removing therefrom the chain bar and clutch drum andmounting the brushcutter attachment thereon with a substitute clutchdrum.

Paten tecl Oct. 13, 1910 3,533,456

INV ENTOR ARSHAG HOVHANNESIAN ATTORNEY.

BRUSI'ICUTTER ATTACHMENT FOR CHAIN SAW ENGINE DRIVE The presentinvention relates to portable power tools, and particularly to anattachment whereby a brushcutter mechanism may be adapted to utilize awide variety of commercially available chain saw engines as a powersource.

BACKGROUND OF THE INVENTION The utility and commercial success ofportable power tools may be greatly enhanced by adapting a tool, or aparticular part thereof, to a widened variety of uses. The greater thenumber of tasks that may be performed by a particular tool, the greaterthe value and marketability thereof. Interchangeability between parts ofdifferent tools can contribute greatly to widening the practical uses ofa tool thereby enhancing its value. For example, if a single powersource, such as an internal combustion engine or an electric motor,there would result an improvement adapted to have attached thereto avariety of operating instrumentalities, e.g., drills, saws, sandingattachment, etc., thereby greatly expanding the utility of eachindividual part and providing a combined mechanism featuring highversatility and economy of cost.

However, a prime prerequisite of such interchangeability is simplicity.The attachment must be such that they can be quickly engaged by the userwith facility and ease.

Accordingly, it is the object of the present invention to provide meanswhereby a brushcutter mechanism may be adapted to utilize a variety ofchain saw engines as a driving mechanism.

The brushcutter mechanism intended for use in the preferred embodimentof the present invention is similar, in many important respects, to thedevice described in U.S. Pat. No. 2,397,457 to Benjamin F. Lawrencewhich is assigned to the same assignee as the present invention. Themethod of operation by a user described in the patent to Lawrencepertains to the present invention, which may be operated in a basicallysimilar fashion. Also the brushcutter mechanism discussed herein,although differing in many essential respects from the Lawrenceinvention, nevertheless may be constructed to comprise similarstructural details. The differences and similarities will be betterunderstood in light of the description which follows.

SUMMARY OF THE INVENTION Briefly, the present invention comprises anarrangement whereby a power tool, such as a brushcutter attachmenthaving a brushcutter operating instrumentality attached to one end, maybe adapted to be mounted upon and receive power from a commerciallyavailable chain saw engine.

More specifically, the end of the brushcutter attachment opposite theend comprising the operating instrumentality is mounted to be driven bya chain saw engine by removing from the chain saw engine the clutch drumand chain bar, and replacing these members with a substitute clutch drumaccording to the present invention which, together with powertransmission stud means, is adapted to transmit power to the drive shaftof the brushcutter attachment which is mounted upon the chain sawengine.

BRIEF DESCRIPTION OF THE DRAWING A better understanding of the inventionmay be had by reference to the following detailed description of apreferred embodiment thereof taken in connection with the accompanyingdrawings wherein:

FIG. 1 is an isometric fragmented view showing the individual parts ofthe present invention together with parts of a chain saw in dotted form;

FIG. 2 is a more detailed isometric view illustrating the mounting ofthe brushcutter attachment to the chain saw engine; and

FIG. 3 is an isometric view of the assembled embodiment described hereinwith the brushcutter attachment mounted to the chain saw engine and inposition to receive driving power therefrom.

DESCRIPTION OF THE PREFERRED EMBODIMENT The drawing depicts a chain sawinternal combustion engine 10 shown in dotted form and shaped simply asa rectangular box. Since the present invention is intended for use witha variety of chain saw engines, and since the particular shape andconfiguration of chain saw engines can vary and would form no part ofthe present invention. except as will hereinafter be described, it isconsidered appropriate for simplicity of description and understandingto depict the chain saw engine 10 as indicated. Other parts of the chainsaw which must be removed therefrom prior to attachment of the elementsforming the present invention are shown in dotted form in FIG. 1. Theseparts are the chain bar I2 and the clutch drum 14.

The parts of the chain saw engine 10 which are important for purposes ofthe present invention are the centrifugal clutch 16 and the mountingstuds 18 and 20. The centrifugal clutch 16 is of a type well known inthe art and well within the knowledge of anyone of ordinary skill in theart. The clutch comprises a pair of shoes 22 and 24 mounted about anengine drive shaft 26. When the engine 10 increases in speed, the shoes22, 24, are forced radially outwardly by centrifugal force away fromdrive shaft 26 and against the biasing force of spring means (notshown).

The clutch drum 14 includes a sprocket means 15 and in the normaloperation of the engine 10 as a chain saw drive means, the clutch drumI4 is mounted and locked upon drive shaft 26 by means of nut 28 andflatwasher 30. With the clutch dram I4 mounted upon drive shaft 26, theinner surface of the clutch drum is adapted to be frictionally engagedand rotatively driven by shoes 22 and 24 when the appropriate speed isreached. The chain bar 12 at its mounted end 13 is adapted to have thechain 47 engage the sprocket means 15 thereby driving the chain 47during cutting operations.

The chain bar 12 is also mounted upon the face of the engine over driveshaft 26 and is locked in place and supported upon studs 18 and 20 bynuts 32, 34 and flatwashers 36, 38,. It should be noted that inutilizing the elements of the present invention as will hereinafter bedescribed the same nuts 28, 32 and 34, and flatwashers 30, 36 and 38, asare supplied with the chain saw may be used.

When it is desired to convert the unit from a chain saw to a Ibrushcutter, it is necessary to merely loosen nuts 28, 32 and 34 andremove the chain bar 12 and the clutch drum l4 and subsequently mountupon the engine 10, in accordance with the present invention, asubstitute clutch drum 40 and a power tool such as a brushcutterattachment generally labelled 50, in a manner to be describedhereinafter.

The substitute clutch drum 40 is mounted upon drive shaft 26 and isdriven by centrifugal clutch 16 in a manner similar to that involvingclutch drum 14. The basic difference between clutch drum l4 andsubstitute clutch drum 40 is that substitute clutch drum 40 does notutilize a sprocket means to transmit power, but rather comprises aplurality of orifices 42 which may be engaged by mating studs. However,the inner surface of substitute clutch drum 40 is adapted to befrictionallyengaged by shoes 22, 24 in a manner similar to the operationof clutch drum 14 previously described, and after replacement of clutchdrum 14 by substitute clutch drum 40 upon drive shaft 26, and lockingthereon by replacement of nut28 and flatwasher 30, the substitute clutchdrum 40 will be in place to receive power when the speed of engine 10reaches an appropriate level.

The brushcutter attachment 50 comprises an elongated tubular member 52whose cutting end has mounted thereon a operating instrumentality suchas a circular saw 58. The housing 54 may have mounted therein anyappropriate gear arrangement whereby power is transmitted from shaft 56to saw 58. The particular gear arrangement utilized will be within theordinary mechanical skill of someone having ordinary knowledge in theart, and forms no part of the present inven tion. One gear arrangementwhich may be utilized is described in the aforementioned patent toLawrence.

The shaft 56 is rotatably mounted within member 52 by appropriatebearing means (not shown) and terminates at the end thereof opposite saw58 within a clutch housing 60. The bearing means utilized and the methodof mounting shaft 56 within member 52 may likewise be similar to thearrangement described in the Lawrence patent. A plate 62 having studs 64fixedly mounted thereon is rotatably situated within housing 60, withthe plate 62 being affixed to shaft 56 by any suitable means, e.g., bybeing integrally formed therewith or by a slot and key arrangement (notshown).

The housing 60 has integrally formed thereon a mounting plate 66comprising orifices 68 and 70 which are adapted to have studs 18 and 20extend therethrough.

When mounting the brushcutter attachment 50 onto the chain saw engine10, the studs 64 are inserted into orifices 42 in substitute clutch drum40 which has been previously mounted onto drive shaft 26 and locked inplace by nut 28 and washer 30. The orifices 68 and 70 will be alignedwith and mounted upon studs 18 and 20 respectively, with the threadedends 19 and 21 extending a sufficient distance beyond the surface ofplate 66 to permit engagement thereof by nuts 32 and 34. With theelements in place, the flatwashers 36 and 38, and the nuts 32 and 34 maybe appropriately mounted upon studs 18 and 20 with the nuts beingtightened to secure the entire assembly.

The attachment 50 comprises a pair of handles 72 and 74 mounted ontomember 52 which a user may grip, one in each hand, in a manner similarto that described in the Lawrence patent, when operating the device. Athrottle control lever 76 is mounted on handle 74 with a throttle cable78 extending to engine and attached thereto, in a manner well known inthe art, to control the speed at which the engine is operated. Thus, auser may control the speed of rotation of the engine drive shaft 26, andconsequently the operating speed of the saw 58, merely by manipulationoflever 76.

It will be apparent that in the operation of the invention, power istransmitted to drive shaft 26 and when the appropriate rotational speedis reached, the shoes 22, 24 are driven by centrifugal force radiallyoutwardly and into frictional engagement with clutch drum 40 which isthereby caused to rotate. With studs 64 engaging the clutch drum 40 inorifices 42, rotation of drum 40 is imparted to the operatinginstrumentality or saw 58 through shaft 56 and the gear mechanismcontained in housing 54.

It will be found that most chain saw engines are identical in many ofthe dimensions with which the present invention is concerned. Althoughthere may be some variation, it will be seen that the brushcutterattachment 50 and the clutch drum 40 may be readily and economicallyadapted to these variances. For example, most lightweight chain sawengines are identical in respect to the distance from the center of thedrive shaft 26 to the mounting studs 18, 20, as well as the centerdistance between mounting studs. Although there is a good deal ofstandardization in the manufacture of chain saws, some variations may befound to exist, such as a difference in drive shaft diameter or inmounting stud diameter, between one manufacturer and another. Suchvariances, however, may be easily provided for by knowing the name ofthe particular manufacturer of the chain saw with which the brushcutterat tachment is to be used, and specifically providing dimensions, e.g.,clutch drum diameter, to operate with the chain saw engine intended.Thus, a specific size clutch drum 40 may be provided with a particularunit, or a single brushcutter attachment 50 or other similar power toolmay be adapted for operation with an expanded number of chain sawengines merely by providing substitute clutch drums of various sizeswith each unit.

it will be apparent from the foregoing that the present inventionprovides a power tool arrangement of great versatility and expandedeffectiveness, and one which permits the utilization of a readilyavailable power source to a significantly broader range of usage therebygreatly enhancing its value. it should be particularly noted that thechangeover from chain saw to brushcutter can be effected in a mannerfeaturing great simplicity and ease of accomplishment, merely by theremoval of three nuts, i.e., nuts 28, 32 and 34, and the replacement oftwo parts. i.e., clutch drum 14 and chain bar 12, by two other parts,i.e., clutch drum 40 and brushcutter attachment 50. Further, replacementof parts is at a minimum since only a substitute clutch drum 40 and abrushcutter attachment 50 need be provided with the commonly availablechain saw.

lclaim:

l. A power tool arrangement comprising a power source including a driveshaft, driving clutch means receiving power from said drive shaft,driven clutch means adapted to engage said driving clutch means, powertransmission means, stud means interposed in engaging relationshipbetween said power transmission means and said driven clutch means totransmit power therebetween, a power tool including a power tooloperating instrumentality, and means transmitting operative power fromsaid power transmission member to said operating instrumentality.

2. A power tool arrangement according to claim 1 wherein said power toolcomprises a brushcutter attachment consisting essentially of a hollowelongated tubular member having a brushcutter attachment drive shaftrotatively mounted therein, said power transmission means being fixedlymounted to one end of said brushcutter attachment drive shaft, with saidstud means, said power source drive shaft and said brushcutterattachment drive shaft all in parallel relationship.

3. A power tool arrangement according to claim 1 wherein said drivenclutch means defines stud engaging orifice means said power transmissionmember means having said stud means mounted thereon in matingrelationship with said stud engaging orifice means for effecting powertransmission between said driven clutch means and said powertransmission means.

4. A power tool arrangement according to claim 1 wherein said stud meansare integrally formed upon said power transmission means and arecircumferentially spaced about the axis of rotation of said power sourcedrive shaft to rotate thereabout in a circular path.

5. A power tool arrangement according to claim 2 including a housingmember integrally formed upon said hollow elongated tubular member, saidhousing member enclosing said driven clutch means and said powertransmission means and having formed integrally therewith a mountingplate defining orifice means engaging said power source to effectmounting of said brushcutter attachment thereon.

6. A power tool arrangement according to claim 5 wherein said powersource is a chain saw engine which includes a plurality of mountingstuds said mounting plate orifice means being aligned to engage saidchain saw mounting studs, and being at least as great in number as saidchain saw mounting studs.

7. A power tool arrangement according to claim 6 wherein said powersource drive shaft, said brushcutter attachment drive shaft, said studmeans and said chain saw mounting studs are parallel, with said mountingplate orifice means and said stud means being relatively spaced tosimultaneously engage, respectively, said chain saw mounting studs andsaid stud engaging orifice means.

8. A power tool arrangement according to claim 7 comprising a conicallyshaped extension integrally formed upon said hollow elongated tubularmember, a rectangularly shaped extension integrally formed upon saidconically shaped extension, orifice means defined by said rectangularlyshaped extension and aligned to engage said chain saw mounting studs 10.A power tool arrangement according to claim 2 wherein said power sourcedrive shaft, said driving clutch means, said driven clutch means, saidstud means and said brushcutter attachment drive shaft are allconcentrically arranged to rotate about the same axis.

